Paul Dano, from left, Brian Wilson and John Cusack arrive at the LA Premiere Of "Love & Mercy" at the Samuel Goldwyn Theater on Tuesday, June 2, 2015, in Beverly Hills, Calif. (Photo by Rob Latour/Invision/AP)
(The Associated Press)

Paul Dano arrives at the LA Premiere of "Love & Mercy" at the Samuel Goldwyn Theater on Tuesday, June 2, 2015, in Beverly Hills, Calif. (Photo by Rob Latour/Invision/AP)
(The Associated Press)

LOS ANGELES – With a shuffling gait and wearing jeans, sneakers and a blue plaid shirt that matches his eyes, Brian Wilson is at the center of a Hollywood whirlwind.

This day, he's been rushing to screenings, giving interviews and posing for photos at a Los Angeles hotel as his new biopic prepares to hit theaters on Friday.

"It's a trip," Wilson says.

Ten years in the making, "Love & Mercy" takes an unflinching look at Wilson's powerful creative energy and debilitating mental illness, demystifying the man who created the sunny sounds of the Beach Boys before descending into a dark world of personal demons.

"The first time I watched it, it was like a real test for my emotions," Wilson said in his typical clipped diction. "It portrays me so well that I felt like I was being pushed into the movie."

That meant re-experiencing some of his highest highs and lowest lows. "Love & Mercy" focuses on two formative periods in the musician's life, separated by 20 years.

Paul Dano plays the younger Wilson at perhaps the peak of his creative genius, when he stayed behind from the Beach Boys' world tour to create his opus "Pet Sounds."

Feeling confined by surf music and inspired by the Beatles' 1965 album "Rubber Soul," Wilson wanted to expand the Beach Boys' sound and give form to the melodies and harmonies he imagined.

He employed an orchestra, climbed inside a piano to plink its strings with a bobby pin, and incorporated everyday sounds like keys jangling or dogs barking into the songs.

Commercially disappointing at first, "Pet Sounds" is now considered one of the most influential compositions in popular music. But it was such a sonic departure that it caused a rift in the band, which exacerbated an emerging personal crisis for Wilson. He began showing signs of mental illness, hearing cacophonous voices and sounds in his head.

John Cusack plays Wilson in the 1980s, a broken man, heavily medicated and terribly insecure, under constant watch by his Svengali-like psychotherapist, Eugene Landy (Paul Giamatti). While shopping for a Cadillac, the troubled musician forms an instant connection with saleslady Melinda Ledbetter (Elizabeth Banks), who would go on to liberate him from Landy's care and become Wilson's second wife.

Director Bill Pohlad interweaves the two narratives, creating a portrait both painful and triumphant.

"I was looking at how to get into the story in a way that wasn't a typical biopic. I hate that," said Pohlad, a longtime producer whose credits include "Wild" and "12 Years A Slave." ''If we were going to do a movie about Brian, I wanted it to be intimate. I wanted to know what this guy was all about."

Wilson and Ledbetter were involved with the making of the film, spending time and sharing personal stories with the director and his cast.

Wilson said he was nervous about the movie and found parts of it upsetting to watch ("Some of it was pretty rough"), but he also came away inspired — reminded, perhaps, of that feeling of all-encompassing creativity.

"I can see Paul Dano doing it in the studio, but I cannot remember actually recording in the studio," Wilson said. "It brings back memories, like 'How could I have done that?!'"

"That was probably my favorite week of acting ever," Dano said, "doing those scenes in the studio where he recorded 'Pet Sounds' in the '60s."

Already a guitarist, Dano learned to play piano for the role and also does his own singing on screen.

Though he and Cusack each spent ample time with Wilson, both actors said they gleaned much of their insight into him by listening to his music.

"That's what brought me closest to the character, was playing and singing for sure," Dano said. "He's in his music."

Both actors said they were honored to portray such a sensitive, intuitive and creative character, and that spending time with him was its own source of inspiration and light.

"I also think about a guy who's that free and unformatted, because those people are very important for us," Cusack said. "When you see his music, you see he's a spirit — a celestial spirit that can do anything, his imagination brings it — and we need those north stars."

As for Wilson, who suffers from schizoaffective disorder, he says these days, exercise makes him happy — "I go to a park and walk and walk and walk" — and, of course, music. He's preparing to tour the U.S. this summer and the U.K. in the fall.

Though he's having an "off period" where he hasn't written for a few months, the 72-year-old knows there's more music in him. It's his language, he said, his means of communication.

"It's all done through music, that's how I explain it," Wilson said. "As a person, I couldn't explain nothing. But with music, I can explain something."